In recent years, the number of vehicles using a voltage higher than 12 V, such as hybrid vehicles, is increasing. For example, a vehicle using a 12 V multiple voltage uses several batteries that each have 12 V and are connected in series.
Since the vehicle may secure a normal operation only when a battery voltage is within a predetermined range, the vehicle controls battery charging and monitors whether the battery has a problem by detecting a voltage, a current, and a temperature of the battery by an intelligent battery sensor (IBS).
The IBS for detecting a 12 V multiple voltage battery according to the related art may only measure a total voltage of the batteries by monitoring a battery voltage of 24 V using one 12 V dedicated application specific integrated circuit (ASIC), but may not detect a voltage imbalance between the batteries.
FIG. 1 illustrates a battery monitoring system to which a battery sensor for monitoring a voltage of 24 V is applied according to the related art.
Referring to FIG. 1, the battery sensor according to the related art includes a voltage dividing resistor Rd, an ammeter resistor Rs, a first integrated circuit IC1, and a second integrated circuit IC2.
Here, the battery sensor is mounted between a second battery and a ground of a vehicle. That is, the ammeter resistor Rs is connected in series between a negative electrode of the second battery and the ground of the vehicle.
The first integrated circuit IC1 measures a total voltage of both terminals of the first battery and both terminals of the second battery and measures a one-directional current flowing in the first battery and the second battery based on values obtained by measuring voltages applied to both terminals of the ammeter resistor Rs.
The second integrated circuit IC2 measures a voltage of the second battery and measures the other-directional current flowing in the first battery and the second battery based on values obtained by measuring voltages applied to both terminals of the ammeter resistor Rs.
The voltage of the first battery is calculated by subtracting the voltage of the second battery measured by the second integrated circuit IC2 from the total voltage measured by the first integrated circuit IC1.
Meanwhile, the battery sensor according to the related art is available only when being mounted between the battery and the ground of the vehicle. In this case, a length, a direction, and the like of a ground cable of the vehicle are varied depending on a kind of vehicle, and therefore it is difficult to share a battery sensor.